Virginia's Declaration of Rights was drawn upon by Thomas Jefferson for the opening paragraphs of the Declaration of Independence. It was widely copied by the other colonies and became the basis of the Bill of Rights.
The ridges found in flexible metal duct create turbulence and will diminish airflow. NEVER use 4 dryer duct or any plastic duct on a range hood installation. The minimum size duct allowed on most range hoods is 3 Â¼ by 10 which is equivalent to 6 round. More powerful hoods require even larger duct sizes up to 10 round. Consult the specifications for the model you have chosen.
The basic rule of thumb when determining the fan size of a range hood is that it should move a minimum of 100 CFM of air for every 12â of stove width. So if you have a 30â wide stove, you would need a range hood with a fan that moves at least 250 CFM of air: